A hard disk drive write driver circuit is described that can change the output impedance of the write driver by use of a lookup table of control values. A control value is selected from the lookup table by using an address based on a dynamic system variable and a program controlled value. The dynamic system variable is converted to a digital representation. The digital representation and a portion of the program controlled value are used as an address to the lookup table to select a control value. The write driver is responsive to the selected control value to control overshoot current. A method to digitally program the output impedance of a preamp write driver based on realistic operating data is also discussed. An additional approach to controlling overshoot current in a write driver through digital control of overshoot duration is also described.